(1) Field of the Invention
The present invention relates to a zeolite-containing non phosphate granular detergent composition, suitable for use in washing fabrics or clothes, which has both good detergency and powder properties, neverthless no phosphate which functions as a detergent builder is contained in the composition.
(2) Description of the Prior Art
Conventional granular detergent compositions heretofore used domestically, as laundry detergents, in washing fabrics or clothes mainly contain, as a detergent builder, condensed phosphates such as tripolyphosphates, pyrophosphates and the like. However, it is well-known that the use of phosphates tends to be restricted from the point of view of the protection of the natural environment which is adversely affected by the phosphates. In view of these recent trends, various new detergent builders which can be substituted for the phosphates have been proposed in the art. Of these proposed detergent builders, type A zeolites (alumino silicates) are remarkably noted as a new builder which can be substituted for conventional phosphates, since the type A zeolites have a high capacity to capture a calcium ion or a mangesium ion in hard water and also have a good builder effect on detergency (or detergent power) (see British Patent Specification Nos. 1473201, 1473202 and 1429143).
However, the type A zeolites (which are simply referred to as "zeolites" hereinbelow), different from the phosphates, are water-insoluble. Therefore, when soiled or stained articles are washed with granular detergent compositions containing zeolites, the deposit of the zeolites is adhered to the articles to be washed (i.e. deposits on fabrics or clothes). Especially, when colored articles are washed, there is a problem that the deposits appear as outstanding undesirable white spots. It is known that the deposits of zeolites on fabrics or clothes are especially remarkable when the zeolites are used together with sodium silicate.
In order to reduce the deposits on fabrics or clothes, various methods have been proposed. For instance: (i) the amount of the sodium silicate incorporated into a detergent composition is decreased to 3% or less, as disclosed in U.S. Pat. No. 3,985,669; (ii) the molar ratio of Na.sub.2 O/SiO.sub.2 in the sodium silicate is increased and also a polyvalent carboxylate is incorporated into a detergent composition, as disclosed in U.S. Pat. No. 4,180,485: and (iii) the chance of the contact of the zeolites with sodium silicate in the production steps of the granular detergent compositions lessens as much as possible, as disclosed in British Patent Specification No. 2013707. These methods can reduce to some extent, the deposits of the zeolites on fabrics or clothes. However, there are other problems in these methods that the powder properties of the granular detergent compositions cannot satisfy and/or the production steps of the granular detergent compositions are troublesome.